Current danger 

Mike Horse threat to Blackfoot clear

The Blackfoot River, one of the most pristine in Western Montana, is a favorite of kayakers and fly-fisherman, and on hot summer days there’s no better reprieve from the heat. Unfortunately, a decaying dam at its headwaters threatens the health of this liquid jewel…again.

In June 1975, Blackfoot floodwaters breached the tailings impoundment at Mike Horse mine near Lincoln, releasing approximately 200,000 cubic yards of metal-bearing tailings. Fine-grain metal-laced tailings flowed at least 10 miles downstream, covering the streambed, poisoning the water and destroying the native westslope cutthroat trout fishery.

Since the 1975 breach, after which the damn was repaired, little has been done to clean up the contamination, or to remediate future threats. Environmentalists, conservationists and federal and state agencies have characterized the Mike Horse dam and tailings pond as a time bomb.

“It would be just an atrocity if that dam failed and killed the top 10 river miles of the Blackfoot again,” says Tracy Stone-Manning, executive director of the Missoula-based Clark Fork Coalition (CFC).

The CFC will kick off a public-awareness campaign this weekend (expect to see petitioners at Saturday’s public markets) designed to get the word out about the dam and to urge citizens to put pressure on the Forest Service and the state Department of Environmental Quality to force removal of the dam once and for all.

“The really important thing is that the Forest Service and Asarco [the mine’s corporate owner] do this right,” says CFC conservation director and staff attorney Matt Clifford. “They need to do it in a permanent way. No solution done on the cheap that takes care of the problem for now and leaves a problem for later generations is acceptable.”

Heavy rains last month raised concern about the dam as floods washed out Mike Horse Creek Road downstream from the structure. Concern about the dam was already elevated following a Forest Service engineering report released in January that found the dam to be unstable and eroding from the inside. Evidence of that erosion can be seen in the reddish and milky-white rivulets of contaminated water seeping out of the dam’s face. The report states that analyses “suggest the dam is a compromised structure which is experiencing internal erosion,” and recommends the dam be taken out of service.

Exactly what “taken out of service” means and who will pay for it are bones of contention between environmental groups, the DEQ, the Forest Service and the two companies with varying degrees of responsibility for the dam—property owner Asarco, and Arco, which inherited responsibility for the mine when it merged with one-time mine operator the Anaconda Copper Mining Company.

“The dam’s got to go,” says Bruce Farling, executive director of Montana Trout Unlimited. “Probably most—if not all—of the contaminated stuff behind the dam has to go. There’s a whole bunch of other discrete sources of waste material above and below that needs to be removed as well.”

Amber Kamps, Lincoln district ranger for the Helena National Forest, says her agency has to look at all the options before leaping to any conclusions.

“We need to be careful with this decision,” says Kamps. “[The Forest Service] wants to certainly maximize environmental improvements, but we also need to be careful with the taxpayers’ dollars. We need to look at that ultimately in the cost and benefits of what is the best option.”

Options could include shoring up the dam and improving flood protection mechanisms while leaving the tailings where they are.

Another option—removing the dam and getting rid of the tailings entirely—would be a costly process. How costly has yet to be determined. The CFC and Trout Unlimited say no cost is as high as the risk of leaving the dam in place for future generations to deal with.

A major step toward developing a remediation plan took place last week when Asarco submitted a lengthy report to the DEQ. The report is a compilation all of the research, data and analysis that has been done on the site over the last 30 years. Now it’s up to the DEQ to review the report and identify “data gaps,” leading to a final report the DEQ hopes to have completed by August. From there, the DEQ will require Asarco to conduct a remedial investigation and feasibility study (RI/FS) to outline the extent of the contamination and identify options for cleaning it up.

According to the DEQ, Asarco and Arco began a five-year voluntary interim remedial action program at the Upper Blackfoot Mining Complex (otherwise known as the Heddleston Mining District) in September 1993. The companies addressed the glaringly obvious environmental concerns by moving mine waste to three repositories away from surface water, installing water flow controls in adits (mine tunnels) and constructing pretreatment ponds and wetlands to filter out adit discharge.

“What we’re currently finding out is that after several years of interim actions being completed, some of the actions were not as effective as [Asarco/Arco] hoped they would be,” says Denise Martinson, a supervisor with the DEQ’s Hazardous Waste Site Cleanup Bureau. “We’re also seeing problems associated with earlier work. There’s still a lot of work that needs to be done.”

The voluntary remedial program was valuable time wasted, say the CFC and Trout Unlimited.

“The agencies [DEQ and Forest Service] have to be more assertive about recovering more money from Asarco and possibly Arco,” says Farling. “We’ve been pushing since the late 1980s to get that cleaned up. The DEQ under the Racicot and Martz administrations was disappointedly weak-kneed.”

Getting more money is going to be the biggest challenge.

“We’re dealing with a company that is sliding toward bankruptcy,” says Stone-Manning.

Asarco isn’t the only company on the hook for the cleanup, however. The DEQ says Arco is also responsible, and has filed suit seeking payment from Asarco and Arco for past and future costs related to the cleanup.

Kamps wouldn’t comment on Arco, but did say the agency will “go after every responsible party” to do what needs to be done to remediate the site.

“It’s going to be really expensive to do this right,” says Farling. “It makes the most sense that the money should come from the guys responsible for the mess.”

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